The present invention relates to lawn mowers of the mid-size, walk-behind, type known as commercial lawn mowers; and more specifically to control systems incorporated in such mowers. Although particularly suitable for commercial type lawn mowers, the present invention need not be limited to such mowers but will have applicability in other types of mowers.
Prior art mowers of this type typically have two squeeze-type control levers on opposite sides of handle bars controlling the drive and braking to two driving wheels respectively located at the rear of the mower. Each of the drive wheels is driven through an associated drive pulley which is driven through a transmission deriving its power from an engine. Pulley belts interconnect the drive pulleys and the driven wheels respectively, and tension is normally applied to the pulley belts by idler pulleys which are biased into engagement with the pulley belts to establish tension for driving the wheels. When the transmission is shifted into an appropriate gear and the control levers are released, the mower will move forwardly. In order to make a right turn the right hand lever is depressed to disengage the idler pulley from the associated pulley belt and at the same time to apply a brake to the right hand wheel. The mower will turn to the right because the left wheel is still being driven while the right wheel is braked. To make a left hand turn the opposite situation is effected, and to bring the mower to a complete stop, both levers are depressed.
Due to the position of the control levers and the fact that use of the mowers over extended periods can fatigue the hands due to the force necessary for braking, attempts have been made to improve the drive and control system for such mowers. By way of illustration reference may be had to U.S. Pat. No. 4,558,558 Horner et al issuing Dec. 17, 1985 which provides a control system intended to improve the aforementioned system. In the Horner et al system, the idler pulleys controlling tension in the drive pulley belts are normally disengaged from the drive pulley belts so that when the control lever 20 is released, no forward drive is transmitted to the driven wheels. In addition Horner provides a single lever or bail 20 for controlling both of the driven wheels. In order to move forwardly with the mower, the lever 20 is pivoted forwardly. To make a gradual turn, the operator merely presses forward on one end 22 of bail 20. The pulley belt on the side corresponding to the selected end will engage the wheel drive on that side while the other wheel drive remains disengaged and the mower will turn in the direction opposite to the engaged wheel. That is, pushing forward on the right end 22 of board 20 will cause the unit to turn left, and vice versa. To make a sharp turn, the operator presses forward on one end 22 of bar 20 while pulling rearwardly on the other end of bar 20. To apply the brakes to stop ground travel, the operator merely pulls bar 20 evenly to the rear; and to hold the brakes in the engaged position for parking, the operator swings a brake lever 50 forwardly and upwardly from a storage position against tube 38 and wedges the lever 50 against a stationary hand rest 19. The free end of lever 50 has a concave shape to nestle over handrest 19 and remains in place until the operator releases it by pulling back further on bar 20 and returning lever 50 to its storage position against tube 38.